Are you sure you aren't talking about the Turks taking Constantinople?
Even WackyPedia acknowledges the slaughter: http://en.wikipedia.org/wiki/Fall_of_Constantinople
I've seen that phrase before, but always in conjunction with the sack of Constantinople.
I want Constantinople back.
Here's wikipedia's description:
http://en.wikipedia.org/wiki/Siege_of_Jerusalem_%281099%29
"...in the Temple and porch of Solomon men rode in blood up to their knees and bridle reins."
They go on to say
"The slaughter of large numbers of Muslims on the Temple Mount is sometimes dubiously projected into the entire city, with some modern commentators claiming that all or almost all of the inhabitants of the city were killed. There is no eyewitness evidence for such a wholesale slaughter outside the Temple Mount area.